CSS Layout Notes

Box Pattern

Box Sizing

box-sizing:

content-box (initial value).
padding-box.
border-box.

:root {
  box-sizing: border-box;
}

*,
::before,
::after {
  box-sizing: inherit;
}

Box sizing:

Intrinsic Sizing (内在尺寸): 表示元素最终的尺寸表现是由内容决定的, e.g fit-content/min-content/max-content.
Extrinsic Sizing (外在尺寸): 表示元素最终的尺寸表现是由上下文决定的, e.g stretch/-moz-available/-webkit-fill-available.

Box Width

Width Formal Syntax

width:

auto: initial value.
<length>.
<percentage>.
min-content | max-content | fit-content | fit-content(<length-percentage>).

Percentage Width

% width calculate by containing box width:

普通元素的百分比宽度是相对于父元素 content box 宽度计算.
绝对定位元素的百分比宽度是相对于第一个 position 不为 static 的祖先元素 padding box 宽度计算.

Auto Flow Width

Auto flow with css-sizing, fit-content/min-content/max-content/stretch for width/min-width/max-width/height/min-height/max-height/ grid-template-rows/grid-template-columns/flex-basis:

fit-content: grow but not overflow.

.content {
  width: fit-content;
  margin: auto;
}

.button {
  box-sizing: border-box;
  width: calc(100% - 30px);
  width: stretch;
  height: 40px;
  margin-right: 15px;
  margin-left: 15px;
}

.table {
  box-sizing: border-box;
  width: 100%;
  width: stretch;
  table-layout: fixed;
}

Min and Max Width

min-width > max-width > width !important:

/* 480px */
.box-1 {
  min-width: 480px;
  max-width: 256px;
}

/* 256px */
.box-2 {
  width: 480px !important;
  max-width: 256px;
}

Box Height

Flow Height

普通文档流是为限定的宽度和无限的高度设计的 (网页元素的默认布局行为):

行内元素跟随文字的方向从左到右排列, 当到达容器边缘时会换行.
块级元素会占据完整的一行, 前后都有换行.

这导致处理元素高度的方式跟处理宽度不一样:

box-sizing 仍然会影响高度, 但最好避免给元素指定明确的高度. 容器的高度由内容 (子元素) 天然地决定, 而不是容器自己决定.

Percentage Height

% height calculate by containing box height:

容器高度为 auto (initial value) 时, 其高度通常由子元素高度决定: 浏览器为避免高度计算死循环, 会忽略子元素百分比高度声明.
容器高度为一个明确值时, 子元素百分比高度才会生效.

Viewport Height

.my-element {
  height: 100vh; /* Fallback for browsers that do not support Custom Properties */
  height: calc(var(--vh, 1vh) * 100);
}

window.addEventListener('resize', () => {
  // Get viewport height and multiple it by 1% to get a value for a vh unit
  const vh = window.innerHeight * 0.01
  document.documentElement.style.setProperty('--vh', `${vh}px`)
})

Box Aspect Ratio

Things can break aspect-ratio:

Setting both dimensions: setting inline-size and block-size simultaneously.
Stretching element: align-items: stretch.
Content that forces height: inner elements may force the height of the parent.

Box Margin

Auto Margin

CSS2 visual formatting model:

If both margin-left and margin-right are auto, their used values are equal.
If margin-top, or margin-bottom are auto, their used value is 0.

Negative Margin

Negative margin change layout flow:

Negative margin-top/margin-left: pull self up/left.
Negative margin-bottom/margin-right: pull sibling up/left, overlapping self.
Negative margin along float direction: pull self.
Negative margin opposite float direction: pull sibling.

.content {
  float: left;
  width: 100%;
  margin-right: -200px;
}

.sidebar {
  float: left;
  width: 200px;
}

Negative horizontal margin on initial width element make width stretch (just like positive padding):

/* ul width = 100% + 20px */
ul {
  margin-right: -20px;
}

ul > li {
  float: left;
  width: 100px;
  margin-right: 20px;
}

.blockquote {
  margin: 2rem -2rem;
}

Percentage Margin

Percentage margin calculate by containing block inline size (width), include margin-top and margin-bottom.

Collapse Margin

margin collapsing occasion:

Adjacent siblings: 1's margin-bottom with 2's margin-top.
No content separating parent and descendants:
- No border/padding/inline part/BFC created/clear: can't separate parents margin-top from its descendant blocks margin-top.
- No border/padding/inline content/height/min-height: can't separate parents margin-bottom from its descendant blocks margin-bottom.
- Collapsed margin ends up outside the parent.
Empty blocks: no border/padding/inline content/height/min-height to separate block's margin-top from its margin-bottom.

margin collapsing calculation:

正正取大值.
正负值相加.
负负最负值.

margin collapsing prevention:

BFC creation: add overflow: auto to container.
Add padding.
Add border.

Never Collapse

Margin collapsing only happen to normal block box vertical direction:

Line box margin never collapse.
float box margin never collapse.
absolute/fixed positioned box margin never collapse.
flex children.
grid children.

Invalid Margin

display: inline 非替换元素 vertical margin 无效.
display: table-cell/display: table-row 元素 margin 无效: e.g <tr>, <td>.
position: absolute 绝对定位元素未定位方向 (auto) margin: .absolute { top: 10%; left: 30%; } margin-right 与 margin-bottom 改变了外部尺寸, 但无法影响兄弟元素布局.
定高容器子元素的 margin-bottom 或者定宽容器子元素的 margin-right 的定位作用失效.

Box Padding

Percentage Padding

Percentage padding calculate by containing block inline size (width), include padding-top and padding-bottom:

.box {
  position: relative;
  padding: 10% 50%;
}

.box > img {
  position: absolute;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
}

Box Overflow

overflow:

visible.
hidden: 溢出隐藏基于 padding box.
clip.
scroll.
auto.

Box Line Height

Inline Element Line Height

行间距:

半行间距 = (line-height * font-size - font-size) / 2.
行间距 = 第一行下半行间距 + 第二行上半行间距.

Box Line Height Inheritance

line-height 继承:

% 与 em 继承计算值, number 继承数值.
line-height 最好使用 number, 使得子代继承 line-height 时文字正常排版, 不会出现 line-height < font-size 导致文字重叠的现象.
Inline level element: 由于 line-height 可继承, 一般给父元素设置 line-height 即可, 会自动作用至容器内所有内联元素.
Block level element: 由于行框盒子幽灵空白节点的存在, line-height * font-size 会决定 block level element 内部元素的最小高度, e.g <div><span></span></div> 高度不为 0.

Box Vertical Align

Box Vertical Align Values

vertical-align 有效值:

线类: baseline, top, middle, bottom.
文本类: text-top, text-bottom.
上标下标类: sub, super.
数值: 基于 baseline 上移 (正数) / 下移 (负数).
百分比: calculate by line-height.

Box Vertical Align Applies

vertical-align 作用元素:

Inline level element:
- <span>/<strong>/<em>.
- <img>/<button>/<input>.
- ::before/::after.
display: table-cell 元素.
用 display: inline-* 或 display: table-cell 以外的方式创建 Box Formatting Context 后, vertical-align 不再起作用.
当 line-height 过小时, vertical-align 在视觉上失效, 调整 line-height 至足够大时, vertical-align 正常起作用.

Box Model

Box model:

Inline-level box: display 属性为 inline, inline-block, inline-table 的元素, 会生成 inline-level box, 并且参与 Inline Formatting Context (IFC).
Block-level box: display 属性为 block, list-item, table 的元素, 会生成 block-level box, 并且参与 Block Formatting Context (BFC).
Flex Formatting Context (FFC).
Grid Formatting Context (GFC).

Inline Box Model

Inline box model:

Not break onto a new line.
width and height properties will not apply.
Vertical padding, border and margin will not push away other inline boxes.
Horizontal padding, border and margin will push away other inline boxes.

Inline Block Element

display: inline-block:

Not break onto a new line.
width and height properties are respected.
padding, border and margin will push away other elements.

Content Area

Character box/em-box/selection box:

一种围绕文字看不见的盒子, 其大小仅受字符本身特性控制, 一般将选中区域等价于此盒子.

Inline Box

内联元素形成外部内联盒子, 让元素不成块显示, 而是排成一行.
水平间距可通过 padding-inline/border-inline/margin-inline 调整, 垂直间距可通过 line-height/vertical-align 调整, 垂直间距不受 padding-block/border-block/margin-block 影响.
<span>/<a>/<em> tag 会产生一般内联盒子.
Bare text 会产生匿名内联盒子.

::first-line {
  color: white;
  background: red;
}

Line Box

每一行会形成一个行框盒子.
每个行框盒子的前面有一个幽灵空白节点 (zero-width inline box with the element's font and line height properties). 父元素的 line-height 会幽灵空白节点产生作用.
将内联元素设置为 display: inline-block 可以消除幽灵空白节点.

Lines containing Box

<p> tag 会形成一个包含盒子, 此盒子由一行一行的行框盒子组成.

Box Height

在很多情况下, 容器高度莫名奇妙变大, 都是行框盒子幽灵空白节点 (Strut), line-height, vertical-align 共同作用的结果:

容器内部除了显式的内联元素外, 每行还存在幽灵空白节点 (Strut).
line-height 可继承, 且基于 font-size 进行计算.
vertical-align 默认对齐方式为基线对齐 (baseline).

常见例子有:

<div><span></span></div> 高度不为 0: Strut 撑高容器.
<div class="leading-8"><span class="text-2xl">文字</span></div> 高度不为 32px (leading-8): 当 Struct font-size 与内联元素 font-size 差距过大时, 进行文字对齐时会撑高容器.
<div><img src="1.jpg"></div> 下边缘存在空隙: Strut 默认基于基线对齐.

Block Box Model

Block box model:

Break onto a new line.
Extend in inline direction to fill space available in its container.
width and height properties are respected.
padding, border and margin will push away other elements.

Block Formatting Context Features

BFC 包含创建该上下文元素的所有子元素 (包含性):

包含内部所有元素的上下外边距: 它们不会跟 BFC 外部的元素产生外边距折叠 (avoid margin collapse).
包含内部所有的浮动元素: 计算 BFC 的高度时, 浮动元素也参与计算 (avoid height collapse).
不包含创建了新 BFC 的子元素的内部元素.

BFC 是页面上的一个隔离的独立容器 (隔离性):

BFC 不会跟外部的浮动元素 (float box) 重叠: 可用于实现自适应布局.
BFC 内部的元素与外部的元素相互隔离, 无法相互影响.
一个元素不能同时存在于两个 BFC 中.
内部的 Box 会在垂直方向, 一个接一个地放置.
每个元素的 margin box 的左边, 与包含块 border box 的左边相接触.
某些情况下，BFC 中的内容可能会与其他 BFC 中的内容重叠:
- 内容太宽, 溢出了容器.
- 设置负外边距, 导致内容被拉到容器外部.

Block Formatting Context Creation

根元素或其它包含它的元素.
overflow: not visible (e.g hidden).
position: not static/relative (e.g absolute/fixed).
float elements.
display: inline-block.
display: table-cell/table-caption/table-*h.
display: flow-root.
Flex items: direct children of flex/inline-flex box.
Grid items: direct children of grid/inline-grid box.

.bfc-1 {
  overflow: hidden;
}

.bfc-2 {
  display: table-cell;
  *display: inline-block; /* For IE7 */
  width: 9999px;
  *width: auto; /* For IE7 */
}

Box Stacking

Stacking Level

Positioned element (non-static position), flex box, grid box can use the z-index property to adjust its stacking level:

数值越大, 处于可视的优先级越大.

Stacking Context

Stacking context creation:

The root element <html> forms the root stacking context.
absolute/relative element with non-auto z-index.
fixed/sticky element.
flex children with non-auto z-index.
grid children with non-auto z-index.
opacity < $100\%$ element.
non-normal mix-blend-mode element.
transform element.
perspective element.
clip-path element.
mask/mask-image/mask-border element.
filter element.
backdrop-filter element.
isolation: isolate element.
will-change above properties element.
contain strict/content/layout/paint element.

The z-index of elements inside of a stacking context are always relative to parent current order in its own stacking context.

<!-- .bottom > .inner is on top -->
<div class="top">
  <div class="inner"></div>
</div>
<div class="bottom">
  <div class="inner"></div>
</div>

<style>
  .top,
  .bottom {
    position: relative;
    width: 250px;
    padding: 80px 20px;
  }

  .top {
    z-index: 1;
  }

  .bottom {
    z-index: 2;
  }

  .top > .inner {
    z-index: 999;
  }

  .bottom > .inner {
    z-index: 2;
  }
</style>

Stacking Order

The background and borders of the root element.
Descendant non-positioned blocks, in order of appearance in the HTML.
Descendant positioned elements, in order of appearance in the HTML.

.box {
  /* 创建层叠上下文 */
  position: relative;
  z-index: 0;
  background-image: url('1.png');
}

.box::before,
.box::after {
  position: absolute;
  z-index: -1;
  content: '';
}

.box::before {
  background-image: url('2.png');
}

.box::after {
  background-image: url('3.png');
}

<div class="container">
  <div class="page">标题和内容</div>
</div>

<style>
  .container {
    /* 创建层叠上下文 */
    position: relative;
    z-index: 0;
    background-color: #666;
  }

  .page {
    position: relative;
    background-color: #f4f39e;
  }

  /* 边角卷边阴影 */
  .page::before,
  .page::after {
    /* 层叠上下文（灰色背景）之上, 定位元素（黄色纸张）之下 */
    position: absolute;
    z-index: -1;
    width: 90%;
    height: 20%;
    content: '';
    box-shadow: 0 8px 16px rgb(0 0 0 / 30%);
  }

  /* 边角卷边阴影定位和角度控制 */
  .page::before {
    bottom: 0;
    left: 0;
    transform: skew(-15deg) rotate(-5deg);
    transform-origin: left bottom;
  }

  .page::after {
    right: 0;
    bottom: 0;
    transform: skew(15deg) rotate(5deg);
    transform-origin: right bottom;
  }
</style>

Inline Pattern

Inline Element Height

内联元素默认的高度完全受 font-size 大小控制.
内联元素没有可视宽度和可视高度 (clientHeight/clientWidth always 0), 垂直方向的行为表现完全受 line-height 和 vertical-align 的影响.

Inline Element Baseline

Inline Block Element Baseline

inline-block element:

内部没有内联元素, 或者 overflow not visible: 其基线为 margin 底边缘.
内部存在内联元素: 其基线为最后一行内联元素的基线.

Vertical Align Baseline

Inline element 与父元素下边缘存在空隙, 原因在于文字排版的基线 (baseline) 对齐机制:

在标准模式中, Inline Formatting Context 总是会包含类似字母 'g'/'f' 尾巴伸出部分空间 (针对下行字母).
<img>/<a> inline element 与父元素底部若干像素间隙, 实际上是此种情况下的字母尾巴预留机制: 行框盒子存在幽灵空白节点, 默认基于 baseline 对齐 (小写字母 x 底部).

清除间隙的方法:

清除 Strut 高度: 父元素 font-size: 0 / line-height: 0, 设置 Inline Formatting Context 高度为 0.
改变对齐方式: 子元素 vertical-align 设置为 top/middle/bottom.
清除 Strut 节点: 子元素 display 设置为 inline-block/block, 创建 Block Formatting Context, 直接清除幽灵空白节点.

可以用以上方法解决 <img> image 5px problem 或相似问题.

Inline Element Padding

可以在不影响当前布局的情况下, 通过增加垂直方向的 padding, 增加链接 (inline) 或按钮 (inline-block) 的点击区域大小:

article a {
  padding: 0.25rem 0;
}

Inline Element Margin

非主动触发位移的内联元素是不会位移至计算容器外部, 内联元素 margin-top 设置过大时 margin-top 会直接失效, 内联元素依然会处于基线对齐位置.

Position Pattern

Static Position

Normal flow.
top/bottom/left/right/inset/z-index have no effect.

Relative Position

使元素相对于 static 布局.
可使用 top/bottom/left/right/inset 属性进行定位.
相对方向 (opposite) 的定位同时设置: top 覆盖 bottom, left 覆盖 right.
初始位置被保留 (仍占用原始空间), 不脱离文档流.

Absolute Position

使元素相对于 containing block 布局:
- Non-static position element.
- transform element.
- perspective element.
- will-change: transform/will-change: perspective element.
- filter element.
- backdrop-filter element.
- contain strict/content/paint element.
若祖先全为无法构成 containing block 的元素, 则使元素相对于浏览器窗口布局.
可使用 top/bottom/left/right/inset 属性进行定位.
相对方向 (opposite) 的定位同时设置: 若未显示设置该方向的元素大小, 则元素具有流动性, 受 containing block 影响其大小, .fluid { position: absolute; left: 0; right: 0; }.
初始位置不被保留, 脱离文档流.
float computed to float: none.
display:
- inline-table computed to table.
- inline/inline-block/table-* computed to block.

.tooltip {
  position: absolute;
}

.form-alert,
.form-warning,
.form-info {
  position: absolute;
}

.overlay {
  position: absolute;
  top: 0;
  left: 0;
  z-index: -50;
  width: 100%;
  height: 100%;
  background: rgb(0 0 0 / 50%);
}

可以利用 absolute 模拟 fixed 布局:

<html>
  <body>
    <div class="page">滚动内容区域</div>
    <div class="fixed">固定定位元素</div>
  </body>
  <style>
    html,
    body {
      height: 100%;
      overflow: hidden;
    }

    .page {
      height: 100%;
      overflow: auto;
    }

    .fixed {
      position: absolute;
    }
  </style>
</html>

Fixed Position

使元素相对于 containing block 布局:
- Initial containing block: 浏览器窗口, 且不受滑动条影响.
- transform element.
- perspective element.
- will-change: transform/will-change: perspective element.
- filter element.
- backdrop-filter element.
- contain strict/content/paint element.
可使用 top/bottom/left/right/inset 属性进行定位.
初始位置不被保留, 脱离文档流.
float computed to float: none.
display:
- inline-table computed to table.
- inline/inline-block/table-* computed to block.

Sticky Position

position: sticky + top: XXX:

使元素相对于 non-visible overflow 祖先 (nearest scrolling ancestor) 布局: 要利用 position: sticky 实现视窗定位效果, 最好保证祖先全为 overflow: visible 元素, 使得视窗成为其 nearest scrolling ancestor.
若祖先全为 overflow: visible 元素, 则使元素相对于浏览器窗口与 containing block 布局:
- containing block 为 BFC creation element:
  - Block container.
  - Table container.
  - Flex container.
  - Grid container.
- 粘性定位元素在它距离视窗顶部大于 XXX 时, 会按照默认布局, 表现为 relative position.
- 一旦其距离顶部的距离等于 XXX, 元素会固定在窗口顶部, 表现为 fixed position.
粘性定位元素不能超出粘性约束矩形范围的限制:
- 当 containing block 移动到窗口外时, 粘性定位元素也会跟着消失.
- 黏性定位元素在同一个容器下会重叠, 在不同容器下则会依次推开: 黏性定位元素分布在一个容器时, 共用一个巨大的黏性约束矩形, 黏性定位元素分布在不同容器时, 存在多个竖直排列的黏性约束矩形.
- 若粘性定位元素父元素的高度和粘性定位元素的高度相同, 则垂直滚动时, 粘性定位效果始终不会出现.
- 可以利用这一特性, 实现层次滚动/视差滚动效果 (Parallax).

.sticky {
  position: sticky;
  top: 0;
  margin-top: 50px;
}

Percentage Position

Positioned elements percentage top/bottom/left/right/inset calculate by containing block height:

If containing block height is auto, it calculated to 0.

Position Reference

position property impact on display items.

Float Pattern

Float Element

包裹性:
- 宽度受子元素影响.
- 宽度受 containing block 影响.
块状化并格式化上下文.
没有任何 margin 合并.
破坏文档流: 父级高度塌陷.
浮动元素的浮动参考 (float reference) 是行框盒子:
- 浮动元素在当前行框盒子内定位.
- float: left box is positioned at begin of line box.
- float: right box is positioned at end of line box.
- Non-floaty flow (text) is laid out along edges of floating boxes.
浮动元素与行框盒子不可重叠: 行框盒子会缩短以容纳浮动盒子, 会形成文字环绕效果.

浮动元素与 BFC 一起布局时, BFC 会收缩以容纳浮动盒子, 此时会忽略自己的边界必须接触包含块边界的规则. 可用此特性创建自适应布局:

Float Block Formatting Context

float make element specified value of display:

inline-table computed to table.
inline-flex computed to flex.
inline-grid computed to grid.
inline/inline-block/table-* computed to block.

Fixed Parent

Floating won't work inside fixed or absolute div unless specify width:

.parent {
  position: fixed;
  top: 5px;
  left: 0;
  width: 100%;
}

Float Clear Fix

为父容器 (.row) 添加 .clearfix:

clear 只能作用于 block level element: ::before/::after 默认为 inline level element, display: table 将 ::before/::after 转换为 block level element.
clear: both 本质是让自身不和浮动元素在同一行排列, 并没有真正意义上地清除浮动元素的 float (仍然脱离文档流): ::after 伪元素不与浮动元素在同一行, 其形成的盒子自然而然地撑起了父容器的高度, 使得因浮动元素脱离文档流而塌陷的父容器恢复正常高度.

.clearfix::before,
.clearfix::after {
  display: table;
  content: '';
}

.clearfix::after {
  clear: both;
}

.clearfix {
  *zoom: 1; /* display: inline-block BFC creation for IE7 */
}

Float Clear Fix

Column Pattern

Two Column Pattern

Block Two Column

inline-block + inline-block.

Absolute Two Column

absolute + margin-left: absolute element not in normal flow.
利用父元素 relative 与子元素 absolute 进行布局.

.div-1 {
  position: relative;
}

.div-1a {
  position: absolute;
  top: 0;
  right: 0;
  width: 200px;
}

.div-1b {
  position: absolute;
  top: 0;
  left: 0;
  width: 200px;
}

Float Two Column

float + float.
float + margin-left: block element ignore float element, inline element surround float element.
float + BFC.

.container {
  overflow: hidden; /* BFC creation */
}

.left {
  float: left;
  width: 60px;
  height: 60px;
}

.right {
  margin-left: 70px;
  overflow: hidden; /* BFC creation */
}

Fifty-fifty Two Column

.fifty-fifty-flex {
  display: flex;
  flex-wrap: wrap;
}

.fifty-fifty-flex > * {
  flex-basis: 250px;
  flex-grow: 1;
}

.fifty-fifty-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
}

Three Column Pattern

Absolute Three Column

Position .left and .right with absolute, add margin-left and margin-right to .middle:

<div class="container">
  <div class="left"></div>
  <div class="middle"></div>
  <div class="right"></div>
</div>

<style>
  .container {
    position: relative;
  }

  .left,
  .right {
    position: absolute;
    width: 200px;
  }

  .middle {
    margin: 0 200px;
  }

  .left {
    left: 0;
  }

  .right {
    right: 0;
  }
</style>

Float Three Column

<div class="left"></div>
<div class="right"></div>
<div class="middle"></div>

.left {
  float: left;
}

.right {
  float: right;
}

.middle {
  margin: 0 right-width 0 left-width;
}

Negative Margin

For float element:

Negative margin along the float direction: pull the float element in that direction.
Negative margin opposite the float direction decrease the float area, causing adjacent elements to overlap the float element.

圣杯布局:

HTML: .middle first.
Padding: padding-left and padding-right to .container, min-width: 2 * (leftWidth + rightWidth) to .container.
Float: float: left to .left, .middle and .right (Currently, .middle in row 1, .left and .right in row 2).
Negative margin: margin-left: -100% to .left, margin-right: -rightWidth px to .right (Pull them up to same row with .middle).
Move: right: leftWidth px to .left (Adjust .left position).

<div class="container">
  <div class="middle"></div>
  <div class="left"></div>
  <div class="right"></div>
</div>

.container {
  padding: 0 200px 0 300px; /* padding-left = .left width, same to .right */
}

.container .middle {
  float: left;
  width: 100%;
  background-color: violet;
}

.container .left {
  position: relative;
  right: 300px;
  float: left;
  width: 300px;
  margin-left: -100%;
  background-color: darkblue;
}

.container .right {
  position: relative;
  float: left;
  width: 200px;
  margin-right: -200px;
  background-color: red;
}

Grid Three Column

Three column layout allows full-width content:

.container {
  display: grid;
  grid-template-columns: 1fr min(60ch, calc(100% - 64px)) 1fr;
  grid-column-gap: 32px;
}

.container > * {
  grid-column: 2;
}

.full-bleed {
  grid-column: 1 / -1;
  width: 100%;
}

Multiple Column Pattern

Multiple column layout:

columns:
- <'column-width'> || <'column-count'>.
- 分栏实际数目 = $\min(\frac{\text{width}}{\text{column-width}}, \text{column-count})$ .
column-width: auto | <length>, 期望分栏宽度.
column-count: auto | <integer>, 期望分栏数目.
column-gap: normal | <length-percentage>, 分隔间隙.
column-rule: <'column-rule-width'> || <'column-rule-style'> || <'column-rule-color'>, 分隔线.
column-rule-width (<line-width>): medium | thin | thick | <length>.
column-rule-style (<line-style>): none | hidden | dotted | dashed | solid | double | groove | ridge | inset | outset.
column-rule-color: currentcolor | <color>.
column-span: none | all, 子元素宽度.
column-fill: balance | balance-all | auto, 子元素分布.
break-inside:
- auto: Allows break.
- avoid: Avoids break.

.three-column {
  column-gap: 1em;
  padding: 1em;
  column-count: 3;
}

.three-column > .last-child {
  column-span: all;
}

Flex Pattern

Flex Box Width

最终尺寸计算:

优先级: 最大最小尺寸 > 弹性增长或收缩 > 基础尺寸.
When there is free space left: used size = $\text{flex-basis} + (\text{flex-grow}/\sum\text{flex-grow})$ .
When there is not enough space: used size = $\text{flex-basis} - (\text{flex-shrink*flex-basis}/\sum\text{flex-shrink*flex-basis})$ .

`flex-basis`	`width`	基础尺寸
set	x	`flex-basis`
auto	set	`width`
auto	auto	最大内容宽度

`min-width`	`width`	最小尺寸
set	x	`min-width`
auto	set	min(`width`, 最小内容宽度)
auto	auto	最小内容宽度

.container {
  display: flex;
}

.initial {
  /* width: 100px~200px */
  flex: initial;
  width: 200px;
  min-width: 100px;
}

.none {
  /* width: 200px */
  flex: none;
  width: 200px;
}

.flex1 {
  /* width: left width * 1/3 */
  flex: 1;
}

.flex2 {
  /* width: left width * 2/3 */
  flex: 2;
}

Flex Shorthand Property

flex = none | [<'flex-grow'> <'flex-shrink'>? || <'flex-basis'>]:

flex-grow: <number>.
flex-shrink: <number>.
flex-basis: content | <'width'>.
flex: initial: 属性默认值, 元素会根据自身宽高设置尺寸. 它会缩短自身以适应容器, 但不会伸长并吸收 flex 容器中的额外自由空间来适应容器, equal to flex: 0 1 auto.
flex: none: 元素会根据自身宽高来设置尺寸. 它是完全非弹性的: 既不会缩短, 也不会伸长来适应容器, equal to flex: 0 0 auto.
flex: auto | <'width'>: 元素会根据自身的宽度与高度来确定尺寸, 但是会自行伸长以吸收 flex 容器中额外的自由空间, 也会缩短至自身最小尺寸以适应容器, equal to flex: 1 1 auto | 1 1 <'width'>.
flex: <number>: 元素会被赋予一个容器中自由空间的指定占比, equal to flex: <number> 1 0%.

Flex Shorthand Property Usage

flex: none: 适合设置在内容不能换行显示的小控件元素上, e.g <button>.
flex: auto: 适合基于内容动态适配的布局.
flex: 0: 适用场景较少, 适合设置在替换元素的父元素上.
flex: 1: 适合等分布局.

Flex Children Display

Flexbox 会改变子元素 display 属性值:

Initial Display	Flex Children Display
`inline`/`inline-block`/`block`	`block`
`flow-root`	`flow-root`
`list-item`	`list-item`
`inline-table`/`table`	`table`
`table-*`	`block`
`inline-flex`/`flex`	`flex`
`inline-grid`/`grid`	`grid`

Flexbox 子元素:

均为块级元素:
- vertical-align 无效化.
- 裸文本子元素会变为匿名块级元素 (Text nodes and pseudo elements can be flex children).
float 无效化.
margin 不合并.
支持 z-index (包括 position: static 子元素): z-index 不为 auto 时创建层叠上下文.
absolute 定位子元素会脱离弹性布局.

Flex Flow

flex-flow: <'flex-direction'> || <'flex-wrap'>.

Flex Direction

flex-direction:

row.
row-reverse.
column.
column-reverse.

flex-direction will change flex alignment direction and start line:

Flex Direction

Flex Wrap

flex-wrap:

nowrap: 不换行.
wrap: 换行.
wrap-reverse.

Flex Alignment

Flex Parent Alignment

justify-content, defines alignment along main axis:
- normal: items packed in default position.
- stretch: behaves as flex-start (stretching in main axis controlled by flex).
- space-between/space-around/space-evenly.
- center/start/end/flex-start/flex-end.
- left/right.
align-items, defines alignment (align-self) for cross axis:
- normal: behaves as stretch/start.
- baseline.
- stretch.
- center/start/end/self-start/self-end/flex-start/flex-end.
align-content, aligns flex container's lines within when there is extra space in the cross-axis:
- normal: items packed in default position.
- baseline.
- stretch/space-between/space-around/space-evenly.
- center/start/end/flex-start/flex-end.
*-content adjust parent padding, *-items and *-self adjust children margin.

Flex Parent Alignment

Flex Children Alignment

align-self:
- auto: computes to parent align-items value.
- normal: behaves as stretch/start.
- baseline.
- stretch.
- center/start/end/self-start/self-end/flex-start/flex-end.
order: <number>, 显示顺序, 初始为 0.

Flex Children Alignment

Flex Margin Alignment

Aligning with auto margin:

<div class="parent">
  <div class="child"></div>
</div>

<style>
  .parent {
    display: flex;
  }

  .child {
    /* This will push child to the right of parent border */
    margin-left: auto;
  }
</style>

最后一行左对齐:

.container {
  display: flex;
  flex-wrap: wrap;
  justify-content: space-between;
}

.list {
  margin: 10px;
}

.list:last-child {
  margin-right: auto;
}

Flex Centering Alignment

/* 子元素全部居中对齐 */
.vertical-container {
  display: flex;
  align-items: center;
  justify-content: center;
  height: 300px;
}

.layer {
  display: flex;
  flex-direction: row;
  flex-grow: 1;
  align-items: center;
  justify-content: flex-start;
  margin: 5px;
  background-color: #fff;
  border: 1px solid #000;
}

Flexbox Pseudo Element

Set flex to pseudo elements of flex box will change width of pseudo elements.

.flex {
  display: flex;
}

.flex::before {
  position: relative; /* no need for absolute position */
  display: block;
}

<body>
  <aside></aside>
  <main></main>
</body>

body {
  display: flex;
  height: 100vh;
  margin: 0;
}

aside {
  flex: 0 0 auto; /* inflexible */
}

main {
  flex: 1 1 auto; /* auto flexible */
  overflow: auto;
}

Flex Reference

Flexbox complete guide.
Flexbox alignment guide.

Grid Pattern

Grid Box Width

Grid Item Automatic Minimum Size

Grid item default min-width is set to auto, grid item can't be smaller than its children:

<div class="grid">
  <div class="item">
    <p>Very very very very very long sentence.</p>
  </div>
  <div class="item">
    <p>Very very very very very long sentence.</p>
  </div>
  <div class="item">
    <p>Very very very very very long sentence.</p>
  </div>
  <div class="item">
    <p>Very very very very very long sentence.</p>
  </div>
  <div class="item">
    <p>Very very very very very long sentence.</p>
  </div>
  <div class="item">
    <p>Very very very very very long sentence.</p>
  </div>
</div>

<style>
  .grid {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    grid-gap: 20px;
  }

  /**
   * Grid item default `min-width` is `auto`,
   * 导致 grid item 内的段落完整显示整行长句.
   */
  .item {
    border: 1px solid red;
  }

  /**
   * Grid item 内的段落正常截断.
   */
  .item-fixed {
    /* Method 1 */
    min-width: 0;

    /* Method 2 */
    overflow: hidden;
  }

  p {
    overflow: hidden;
    text-overflow: ellipsis;
    white-space: nowrap;
  }
</style>

Grid Property

Parent property:

grid:
- grid-template:
  - grid-template-rows.
  - grid-template-columns.
  - grid-template-areas.
- grid-auto-rows.
- grid-auto-columns.
- grid-auto-flow.
gap:
- row-gap.
- column-gap.
place-content:
- align-content.
- justify-content.
place-items.
- align-items.
- justify-items.

Children property:

grid-area:
- grid-row:
  - grid-row-start.
  - grid-row-end.
- grid-column:
  - grid-column-start.
  - grid-column-end.
place-self:
- align-self.
- justify-self.

.container {
  grid-template-areas:
    'header header header'
    'advert content content'
    'footer footer footer';
  grid-template-rows: 1fr 1fr 1fr;
  grid-template-rows: minmax(90px, 1fr);
  grid-template-columns: 1fr 1fr 1fr;
  grid-template-columns: repeat(3, 1fr);
  gap: 10px;
  place-items: end center;
}

.item {
  grid-area: footer;
  grid-row: start / end; /* 2 / -1 */
  grid-column: start / end;
  place-self: end center;
}

Grid Data Types

Grid Breadth Types

<track-breadth>:

<flex>: <number>fr, fraction.
<length-percentage>.
min-content.
max-content.
auto.

<inflexible-breadth>:

<length-percentage>.
min-content.
max-content.
auto.

<fixed-breadth>:

<length-percentage>.

Grid Size Types

<track-size>:

<track-breadth> .
minmax(<inflexible-breadth>, <track-breadth>).
fit-content(<length-percentage>).

<fixed-size>:

<fixed-breadth>.
minmax(<fixed-breadth>, <track-breadth>).
minmax(<inflexible-breadth>, <fixed-breadth>).

Grid Repeat Types

<track-repeat>:

repeat([<integer [1,∞]>], [<line-names>? <track-size>]+ <line-names>?).

<fixed-repeat>:

repeat([<integer [1,∞]>], [<line-names>? <fixed-size>]+ <line-names>?).

<auto-repeat>:

repeat([auto-fill | auto-fit], [<line-names>? <fixed-size>]+ <line-names>?).

<name-repeat>:

repeat([auto-fill | <integer [1,∞]>], <line-names>+).

Grid Line Types

<grid-line>:

auto.
<custom-ident>
[<integer> && <custom-ident>?].
[span && [<integer> || <custom-ident>]].

Responsive Grid Layout

Explicit Responsive Grid Layout

fit-content(limit): clamp([min-content | min-width], limit, max-content).
minmax([<fixed-breadth> | <inflexible-breadth>], [<track-breadth> | <fixed-breadth>]).
repeat([<integer [1,∞]> | auto-fill | auto-fit], [<track-size> | <fixed-size>]+).

.container {
  display: grid;
  grid-template-columns: fit-content(var(--sidebar-max, 20ch)) minmax(50%, 1fr);
  grid-template-columns: repeat(auto-fit, minmax(400px, 1fr));
  grid-template-columns: repeat(
    auto-fit,
    minmax(min(100%, var(--grid-min, 30ch)), 1fr)
  );
}

Implicit Responsive Grid Layout

grid-auto-rows/grid-auto-columns:

<track-size>+.
Control implicitly-created grid track (row/column) size.

<div class="container">
  <item>1</item>
  <item>2</item>
  <item>3</item>
  <item>4</item>
  <item class="implicit">5</item>
</div>

<style>
  .container {
    display: grid;
    grid-template: 1fr 1fr / 1fr 1fr;

    /* 隐式网格高度为 60px */
    grid-auto-rows: 60px;
  }
</style>

<div class="container">
  <item class="item-a">a</item>
  <item class="item-b">b</item>
</div>
<style>
  .container {
    display: grid;
    grid-template: 1fr 1fr / 1fr 1fr;

    /* 隐式网格宽度为 60px */
    grid-auto-columns: 60px;
  }

  .item-b {
    /* 超出网格列数, 隐式网格创建 */
    grid-column: 3 / 4;
    background-color: rgb(255 255 0 / 50%);
  }
</style>

Implicit Grid Layout

grid-auto-flow:

[row | column] || dense.
Change auto-placement algorithm: control exactly how auto-placed items get flowed into grid container, like flex-direction for flex container.

.gallery {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(200px, 1fr));
  grid-auto-rows: 1fr;
  grid-auto-flow: dense;
  grid-gap: 1em;
}

Named Grid Layout

Grid Lines

grid-row and grid-column change start and end of <grid-line> will refactor grid item's size and location:

.main {
  display: grid;
  grid-template-rows: [header] 100px [body] auto;
  grid-template-columns: [l-gutter] 1fr [sidebar] 4fr [content] 8fr [r-gutter] 1fr;
  gap: 1rem 2rem;
}

.header {
  grid-row: header;
  grid-column: sidebar / right-gutter;
}

.sidebar {
  grid-row: body;
  grid-column: sidebar;
}

.content {
  grid-row: body;
  grid-column: content;
}

隐式网格线:

<custom-ident>: 当 <custom-ident> 不存在时, 会尝试匹配 <custom-ident-start> 或者 <custom-ident-end>.
<integer> && <custom-ident>: 当第 <integer> 个 <custom-ident> 不存在时, 会在网格容器后方额外创建隐式网格.
span && <custom-ident>: 当 <custom-ident> 不存在时, 会在网格容器前方或者后方额外创建隐式网格.

.container {
  display: grid;
  grid:
    '. . .' 1fr
    '. a .' 1fr
    '. . .' 1fr / 1fr 1fr 1fr;
}

.item {
  grid-area: a;
  grid-area: a / a / a / a;
  grid-area: a-start / a-start / a-end / a-end;
}

.container {
  display: grid;
  grid-template-columns: [a] 80px [b] auto [c] 100px [d];
}

.item {
  /**
   * .container: [a] 80px [b] auto [c] 100px [d] auto [b] auto [b] auto [b]
   * .item: [c] 100px [d] auto [b] auto [b] auto [b]
   */
  grid-column: b 4 / c;
}

.container {
  display: grid;
  grid-template-columns: [a] 80px [c] auto [c] 100px [d] auto auto;
}

.item {
  /**
   * .container: [b] auto [a] 80px [c] auto [c] 100px [d] auto auto
   * .item: [b] auto [a] 80px [c] auto [c] 100px [d]
   */
  grid-column: span b / 4;
}

Extending elements beyond the content area with named grid lines:

.content {
  --gap: clamp(1rem, 6vw, 3rem);
  --full: minmax(var(--gap), 1fr);
  --content: min(50ch, 100% - var(--gap) * 2);
  --popup: minmax(0, 2rem);
  --feature: minmax(0, 5rem);

  display: grid;
  grid-template-columns:
    [full-start] var(--full)
    [feature-start] var(--feature)
    [popup-start] var(--popup)
    [content-start] var(--content) [content-end]
    var(--popup) [popup-end]
    var(--feature) [feature-end]
    var(--full) [full-end];
}

.content > * {
  grid-column: content;
}

.popup {
  grid-column: popup;
}

.feature {
  grid-column: feature;
}

.full {
  grid-column: full;
}

Grid Areas

网格线自动命名: areaName-start/areaName-end.

.container {
  grid-template: 1fr 1fr 1fr 1fr / 1fr 1fr 1fr;
  grid-template:
    'grape grape grape' 1fr
    'apple orange orange' 1fr
    'apple orange orange' 1fr
    'banana banana banana' 1fr
    / 1fr 1fr 1fr;
  grid-template:
    [row-name1-start] 'grape grape grape' 1fr [row-name1-end row-name2-start]
    'apple orange orange' 1fr [row-name2-end]
    'apple orange orange' 1fr [row-name3-end]
    [row-name4-start] 'banana banana banana' 1fr [row-name4-end]
    / [col-name-start] 1fr [col-name-end] 1fr 1fr;
  grid-template-areas:
    'grape grape grape'
    'apple orange orange'
    'apple orange orange'
    'banana banana banana';
}

.grape {
  grid-area: grape;
}

.apple {
  grid-area: apple;
}

.orange {
  grid-area: orange;
}

.banana {
  grid-area: banana;
}

Grid Gap

CSS Box Alignment Module Level 3 统一了分栏布局, 弹性布局, 网格布局的 gap 属性:

gap: <'row-gap'> <'column-gap'>?.
row-gap: normal | <length-percentage>.
column-gap: normal | <length-percentage>.

Grid Alignment

justify-content/align-content content within element, attach to parent css selector (effectively adjusts padding of parent)
justify-items/align-items align items inside box, attach to parent css selector (effectively adjusts margin of children)
justify-self/align-self align element within parent, attach to children css selector (effectively adjusts margin of children)
place-content: <'align-content'> <'justify-content'>?.
place-items: <'align-items'> <'justify-items'>?.
place-self: <'align-self'> <'justify-self'>?.

Grid-Only Alignment Properties

justify-items, defines the default justify-self for all items:
- normal: behaves as stretch/start.
- baseline.
- stretch.
- center/start/end/self-start/self-end/flex-start/flex-end.
- left/right.
justify-self:
- auto: computes to parent justify-items value.
- normal: behaves as stretch/start.
- baseline.
- stretch.
- center/start/end/self-start/self-end/flex-start/flex-end.
- left/right.

Grid Alignment

Grid Pseudo Element

Adding background and border is a missing feature of CSS Grid specification, you can styling empty grid cells and areas with generated pseudo elements:

.grid::after {
  z-index: -1;
  grid-row: 1 / 4;
  grid-column: 2 / 5;
  content: '';
  background-color: rgb(214 232 182 / 30%);
  border: 5px solid rgb(214 232 182);
}

Implement fancy <h1> header:

h1.lines {
  display: grid;
  grid-template-columns: 1fr auto 1fr;
  gap: 1em;
  text-align: center;
}

@supports (display: grid) {
  h1.lines::before,
  h1.lines::after {
    align-self: center;
    content: '';
    border-top: 1px solid black;
  }
}

Conditionally styling selected elements in grid container:

<main>
  <input type="checkbox" />
  <input type="checkbox" />
  <input type="checkbox" />
  <input type="checkbox" />
  <input type="checkbox" />
  <input type="checkbox" />
  <input type="checkbox" />
  <input type="checkbox" />
  <input type="checkbox" />
  <input type="checkbox" checked />
  <input type="checkbox" checked />
  <input type="checkbox" checked />
  <input type="checkbox" checked />
  <input type="checkbox" />
  <input type="checkbox" />
  <input type="checkbox" />
  <input type="checkbox" />
  <input type="checkbox" />
  <input type="checkbox" />
  <input type="checkbox" />
  <input type="checkbox" />
  <input type="checkbox" />
  <input type="checkbox" />
  <input type="checkbox" />
  <input type="checkbox" />
  <input type="checkbox" />
  <input type="checkbox" />
  <input type="checkbox" />
  <input type="checkbox" />
  <input type="checkbox" />
</main>

<style>
  main {
    display: grid;
    grid: repeat(5, 60px) / repeat(7, 60px);
    place-items: center center;
    margin: 0;
  }

  input {
    display: grid;
    width: 40px;
    height: 40px;
    margin: 0;
    appearance: none;
    cursor: pointer;
    background: #ddd;
    border-radius: 20px;
  }

  input:not(:nth-of-type(7n + 1))::before,
  input:nth-of-type(n + 8)::after {
    z-index: -1;
    grid-area: 1/1;
    pointer-events: none;
    content: '';
    border-radius: 20px;
  }

  input:not(:nth-of-type(7n + 1))::before {
    transform: translateX(-60px);
  }

  input:nth-of-type(n + 8)::after {
    transform: translateY(-60px);
  }

  input:checked {
    background: limegreen;
  }

  /* a box's right borders */
  input:not(:nth-of-type(7n)):checked + input:checked::before {
    background: limegreen;
    border-top-right-radius: 0;
    border-bottom-right-radius: 0;
  }

  /* a box's bottom borders */
  input:nth-last-of-type(n + 8):checked
    + *
    + *
    + *
    + *
    + *
    + *
    + input:checked::after {
    background: limegreen;
    border-bottom-right-radius: 0;
    border-bottom-left-radius: 0;
  }

  /* a box's adjacent (right side) box's left borders */
  input:not(:nth-of-type(7n)):checked + input:checked + input::before {
    background: limegreen;
    border-top-left-radius: 0;
    border-bottom-left-radius: 0;
  }

  /* a box's adjacent (below) box's top borders */
  input:not(:nth-of-type(7n)):checked
    + *
    + *
    + *
    + *
    + *
    + *
    + input:checked
    + input::before {
    background: limegreen;
    border-top-left-radius: 0;
    border-top-right-radius: 0;
  }

  /* a box's (in last column) left borders */
  input:nth-of-type(7n-1):checked + input:checked {
    border-top-left-radius: 0;
    border-bottom-left-radius: 0;
  }

  /* a box's (in last column) adjacent (below) box's top borders */
  input:nth-of-type(7n):checked + * + * + * + * + * + * + input:checked {
    border-top-left-radius: 0;
    border-top-right-radius: 0;
  }
</style>

Grid System

Must have different traits at different sizes.
Must be fluid between breakpoints.
Must have enough control to decide which columns will transform and at which point.
Classes should ideally still make sense at all breakpoints.

Grid Reference

Grid complete guide.

Masonry Pattern

Chrome debates on masonry layouts.
Webkit invents masonry layouts for CSS grid level 3.

Alignment Pattern

Height Alignment Pattern

border simulation.
Negative margin.
absolute element: .absolute { top: 0; bottom: 0; } 使所有子元素 (absolute) 与父元素 (relative) 等高.
table layout: display: table-cell 默认等高.
flex layout: flex items 默认拉伸至盒子高度.
grid layout: grid items 默认等高.

Border Simulation Height Alignment

/* 导航背景区 border 创建 */
.box {
  background-color: #f0f3f9;
  border-left: 150px solid #333;
}

/* 清除浮动影响 */
.box::after {
  display: block;
  clear: both;
  content: '';
}

/* 布局主结构 */
.box > nav {
  float: left;
  width: 150px;
  margin-left: -150px;
}

.box > section {
  overflow: hidden;
}

Negative Margin Height Alignment

.column-box {
  overflow: hidden; /* hidden overflow background */
}

/* 视觉等高布局 */
.column-left,
.column-right {
  padding-bottom: 9999px;
  margin-bottom: -9999px;
}

Layout Height Alignment

.table {
  display: table;
  overflow: hidden;

  .left {
    display: table-cell;
    width: 200px;
    background: #4caf50;
  }

  .right {
    display: table-cell;
    width: 800px;
    background: #99afe0;
  }
}

.flex {
  display: flex;
  flex-flow: row nowrap;
  align-items: stretch;

  .left {
    flex: 200px 0 0;
    background: #4caf50;
  }

  .right {
    flex: auto 1 0;
    background: #99afe0;
  }
}

.grid {
  display: grid;
  grid-template-columns: 200px auto;
  align-items: stretch;

  .left {
    background: #4caf50;
  }

  .right {
    background: #99afe0;
  }
}

Centering Pattern

Horizontal Centering Pattern

Horizontal Centering Inline Element

text-align: center.
flex.
grid.

.quote {
  text-align: center;
}

Horizontal Centering Block Element

Auto margin.
flex.
grid.

.row {
  width: 100%;
  max-width: --var(row-max-width);
  margin: 0 auto;
}

.container {
  max-width: 1024px;
  margin: 0 auto;
}

父元素 float, 父子元素 relative:

.container {
  position: relative;
  left: 50%;
  float: left;
}

.container ul {
  position: relative;
  left: -50%;
}

Vertical Centering Pattern

Vertical Centering Inline element

line-height.
vertical-align: middle:
- 作用机制: 对齐基线 (baseline) 往上 1/2 x-height 高度 (即小写字母 x 交叉点处).
- 作用环境: parent element line-height === height.
- 作用对象: children inline/inline-block/table-cell element.
Vertical parent padding.
flex.
grid.

Button label (<a>) vertical alignment (行内块居中法:

a.button::before {
  display: inline-block;
  height: 16px;
  vertical-align: middle;
  content: '';
}

Vertical Centering Block element

top + translateY.
vertical-align: middle + display: table-cell: 表格单元居中法.
Vertical margin.
Vertical padding.
flex.
grid.

.viewport-centered-block {
  width: 18em;
  margin: 50vh auto 0;
  transform: translateY(-50%);
}

.form-item-label {
  display: flex;
  flex-direction: row;
  align-items: center;
}

Mixing Centering Pattern

.box {
  position: absolute;
  top: 50%;
  left: 50%;
  transform: translate(-50%, -50%);
  backface-visibility: hidden; /* Remove blurry in WebKit browsers */
  transform-style: preserve-3d; /* Remove blurry in WebKit browsers */
}

.dialog {
  position: absolute;
  inset: 0;
  width: fit-content;
  height: fit-content;
  margin: auto;
}

Centering Pattern Reference

Centering layout complete guide.

Layout Reference

CSS box model.
CSS layout guide.

Box Pattern​

Box Sizing​

Box Width​

Width Formal Syntax​

Percentage Width​

Auto Flow Width​

Min and Max Width​

Box Height​

Flow Height​

Percentage Height​

Viewport Height​

Box Aspect Ratio​

Box Margin​

Auto Margin​

Negative Margin​

Percentage Margin​

Collapse Margin​

Invalid Margin​

Box Padding​

Percentage Padding​

Box Overflow​

Box Line Height​

Inline Element Line Height​

Box Line Height Inheritance​

Box Vertical Align​

Box Vertical Align Values​

Box Vertical Align Applies​

Box Model​

Inline Box Model​

Content Area​

Inline Box​

Line Box​

Lines containing Box​

Block Box Model​

Block Formatting Context Features​

Block Formatting Context Creation​

Box Stacking​

Stacking Level​

Stacking Context​

Stacking Order​

Inline Pattern​

Inline Element Height​

Inline Element Baseline​

Inline Block Element Baseline​

Vertical Align Baseline​

Inline Element Padding​

Inline Element Margin​

Position Pattern​

Static Position​

Relative Position​

Absolute Position​

Fixed Position​

Sticky Position​

Percentage Position​

Position Reference​

Float Pattern​

Float Element​

Float Block Formatting Context​

Fixed Parent​

Float Clear Fix​

Column Pattern​

Two Column Pattern​

Block Two Column​

Absolute Two Column​

Float Two Column​

Fifty-fifty Two Column​

Three Column Pattern​

Absolute Three Column​

Float Three Column​

Grid Three Column​

Multiple Column Pattern​

Flex Pattern​

Flex Box Width​

Flex Shorthand Property​

Flex Children Display​

Flex Flow​

Flex Direction​

Flex Wrap​

Flex Alignment​

Flex Parent Alignment​

Box Pattern

Box Sizing

Box Width

Width Formal Syntax

Percentage Width

Auto Flow Width

Min and Max Width

Box Height

Flow Height

Percentage Height

Viewport Height

Box Aspect Ratio

Box Margin

Auto Margin

Negative Margin

Percentage Margin

Collapse Margin

Invalid Margin

Box Padding

Percentage Padding

Box Overflow

Box Line Height

Inline Element Line Height

Box Line Height Inheritance

Box Vertical Align

Box Vertical Align Values

Box Vertical Align Applies

Box Model

Inline Box Model

Content Area

Inline Box

Line Box

Lines containing Box

Block Box Model

Block Formatting Context Features

Block Formatting Context Creation

Box Stacking

Stacking Level

Stacking Context

Stacking Order

Inline Pattern

Inline Element Height

Inline Element Baseline

Inline Block Element Baseline

Vertical Align Baseline

Inline Element Padding

Inline Element Margin

Position Pattern

Static Position

Relative Position

Absolute Position

Fixed Position

Sticky Position

Percentage Position

Position Reference

Float Pattern

Float Element

Float Block Formatting Context

Fixed Parent

Float Clear Fix

Column Pattern

Two Column Pattern

Block Two Column

Absolute Two Column

Float Two Column

Fifty-fifty Two Column

Three Column Pattern

Absolute Three Column

Float Three Column

Grid Three Column

Multiple Column Pattern

Flex Pattern

Flex Box Width

Flex Shorthand Property

Flex Children Display

Flex Flow

Flex Direction

Flex Wrap

Flex Alignment

Flex Parent Alignment